I have been grappling with a similar issue. I have a 9 and a 7 and was thinking off going with a 6 instead. I found that the 7 is good 80 percent of the time and a 5 or 6 would be great for hurricane force winds

It depends how much you value your sessions vs. your money. I guarantee that with a 3m split, you'll have some days where you wish you had the kite right in between the two sizes. There's no wrong decision, I'd err towards three kites where the middle one is your "money" machine that you fly 80% of the time, but that's me.

Good point about money vs. session. I'm content with 12m and 9m, but I've only been riding in the Bay. It's almost never so windy that I wish I had something smaller. Last Saturday at the Toll Plaza was one of those rare days--I was a little overpowered on the 9m, but it worked out okay. Not worth it to buy an extra kite or two for those exceptional days where I might need them.